Dysplasia is a very imperfect biomarker for malignancy in Barrett's esophagus. Invasive cancer has been found in 30-40% of esophagi resected because preoperative endoscopic examinations had shown high-grade dysplasia. Reports on the natural history of this disorder are sometimes contradictory, but suggest that 10-30% of patients with high-grade dysplasia in Barrett's esophagus will develop a demonstrable malignancy within 5 yr of the initial diagnosis. Proposed management strategies for high-grade dysplasia include esophagectomy, endoscopic ablative therapies, endoscopic mucosal resection (EMR), and intensive endoscopic surveillance. Endoscopic ablative therapies and EMR may not be effective if neoplastic cells have invaded the submucosa or disseminated through mucosal lymphatic channels, and a number of studies suggest that the endoscopic therapies usually leave metaplastic or neoplastic epithelium with malignant potential behind. Limited data suggest that intensive endoscopic surveillance might be a reasonable approach for elderly or infirm patients, but some patients managed in this fashion have developed incurable esophageal cancers. The fundamental question of what is the appropriate length of follow-up for studies on dysplasia treatments has not been resolved. Although 5 yr might be considered the absolute minimum duration for a meaningful follow-up on dysplasia therapy, the follow-up duration in most studies is substantially less than 5 yr. Specific recommendations for management based on these considerations are proposed at the end of this report.